: Foam pad on a random orbit sander, allows the disc to flex to
: handle the curves.

: Bill H.

An alternative - use a 3M disc attachment for a drill, and place a 5" 'loop' sanding disc to it. But be forewarned - it's not as easily controlled as Bills' recommendation, and it's easy to 'gouge'. I finish off the problem areas with a piece of closed-cell foam wrapped with a piece of sandpaper, usually a sanding disc, as well. Works okay with the interior of a kayak (you won't see the 'sins' ) but.... maybe not 'good enoough' for a canoe.